In recent years, there have many instances of trouble occurring due to the presence of slime in various types of service water traceable to microbial contamination, and adverse effects have been caused in various fields. Here, the term “slime” means a sticky aggregated or muddy substance which comprises as major components high molecular polysaccharides secreted mainly by microbes, and various types of substance suspended in the water which become incorporated therein. For example, when slime occurs in heat exchangers or pipes of a cooling water system at a chemical factory or the like, cooling efficiency is decreased and sometimes pipes are clogged. Further, when slime forms on the wall surfaces of pipes used in the paper manufacturing process at a paper factory, the slime is flaked off and mixed in white water (back water). Then, spots or coloring are formed on the paper product and deteriorate its quality. This partially decreases paper strength and thus causes paper breakages, forcing the interruption of continuous operations. Therefore, the control of the causative microbes is an important issue.
Further, active sludge at sewage treatment plants, unpleasant odors from wastes or residues, and foul odors from raw garbage at waste treatment plants cause not only on-site working environments to be poor, but also deteriorate the environments of surrounding areas by diffusing such odors to these areas. Thus, prompt odor elimination or deodorization by preventing the occurrence of or by the decomposition of causative agents is essential. However, in the case of existing deodorants, the decomposition or volatilization of their chemical components having deodorant effects results in deterioration of their deodorant effects, and the problem thus exists that the sustainability of their effects is low.
Conventionally, chlorine gas, sodium hypochlorite or potassium hypochlorite solution, or chlorinated isocyanuric acid in tablet or powder form has been used in order to prevent trouble caused by such microbes. However, chlorine gas has disadvantages in that it involves very high risk in the case of leakage, and it is difficult to handle. Further, hypochlorous agents are also disadvantageous in that they do not act effectively on microbes since they do not have permeability into slime. These agents have further disadvantages such as deactivation by organic matters in water, and thus sufficient efficacy cannot be expected.
On the other hand, it is known that halogenated dialkyl hydantoins or halogenated succinimides have microbicidal activities (Zn. Mikrobiol., Epidemiol. Immunobiol. vol.14, No.9, p14-18, 1967, JP Patent Publication (Examined Application) No. 46-27270). However, these compounds are commercially distributed in a solid form such as tablet, powder, or granule, and they are used in the solid form in the field. Therefore, when using these compounds, problems arise in handling safety, that is, the risk of effects on humans such as skin disorders and mucosal inflammation caused by dusting during operation. Further, workability problems are presented, such as the inability to transfer these compounds by pump.
Further, from a microbicidal efficacy aspect, these compounds have sluggish solubility and permeability into target systems. Thus, in order to obtain a sufficient effect in a short period, these compounds must be added in a large amount. In particular, when these compounds are used for water systems with low recirculation rates, for example, cooling water for certain industrial uses or water for paper manufacturing processes, water in the systems is discharged out of the systems before the inputted compounds are completely dissolved. In contrast, when these compounds are used for water systems with high recirculation rates, for example, cooling water for air-conditioning, the sluggish rate of dissolution of the inputted compounds increases the probability of the growth of resistant microbes in the system. Also, due to the sluggish rate of dissolution and sluggish permeability of these compounds, prompt deodorizing effects after their input cannot be obtained. Therefore, in the case of using these compounds as deodorants, the addition of large amounts thereof is required, resulting in cost increase.
Most solid compounds having microbicidal activity are used as liquid agent by dissolving them into, in general, glycols, glycol ethers, aprotic polar solvents or water, or mixture solvents of these with water. This allows easy handling of microbicidal solid compounds. Liquidizing microbicidal solid compounds in this manner provides these compounds with excellent workability at the time of use, and at the same time, also provides them with other advantages such as quick dissolution and permeation of active ingredients into target systems to be treated for microbes or deodorization. Namely, in comparison with the case where solid compounds are inputted into the target systems as solid agents, adding smaller amounts of these compounds within a shorter period enables killing of microbes and deodorization in the target systems. Therefore, liquidizing microbicidal solid compounds is an extremely effective means for cost reduction.
However, when halogenated dialkyl hydantoins and halogenated succinimides are prepared as liquid agents with generally used organic solvents, a large volume of irritant corrosive gas is immediately generated. Further, in this case, microbicidal active ingredients are deactivated within a very short period, and thus the compounds can no longer be used as microbicidal and deodorizing agents. In other words, liquid agents containing halogenated dialkyl hydantoins and halogenated succinimides have disadvantages such as corrosive gas generation and poor stability. Furthermore, with regard to liquid compositions containing derivatives of halogenated dialkyl hydantoins, a method using water and cyclic amide compounds including ε-caprolactam and succinimide has been already suggested (JP Patent Publication (Examined Application) No. 56-37961). Although these liquid compositions are better in terms of stability in comparison with liquid compositions prepared using common organic solvents, they do not have sufficient stability as a formulation.
Under these circumstances, there is a need for halogenated dialkyl hydantoin compositions and halogenated succinimide compositions which are liquid for tractability and have excellent stability, i.e. stable in long-term storage. However, a formulated liquid agent suitable for practical use has not been found before.